The awesome 100 Year Starship (100YSS) initiative by DARPA and NASA proposes to send people to the stars by the year 2100 — a huge challenge that will require bold, visionary, out-of-the-box thinking. One possible solution is mind-uploading — what could give rise to highly versatile and resilient software-based astronauts and their e-crews. And at the same time, the development of the requisite technologies could result in important spinoffs in neuroscience, computer science, and longevity — perhaps even including indefinite life extension.

"To make the trip on timescales of a human lifetime, the rocket needs to travel much faster than current probes, at least 5% the speed of light. … It's actually physically impossible to do this using chemical rockets, since you'd need more fuel than exists in the known universe," Icarus Interstellar points out.

So the Icarus team has chosen a fusion-based propulsion design for Project Icarus, offering a million times more energy compared to chemical reactions. It would be evolved from their Daedalus design.

This propulsion technology is not yet well developed, and there are serious problems, such as the need for heavy neutron shields and risks of interstellar dust impacts, equivalent to small nuclear explosions on the craft's skin, as the Icarus team states.

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However, as a reality check, I will assume as a worse case that none of these exotic propulsion breakthroughs will be developed in this century.

That leaves us with an unmanned craft, but for that, as Icarus Interstellar points out, "one needs a large amount of system autonomy and redundancy. If the craft travels five light years from Earth, for example, it means that any message informing mission control of some kind of system error would take five years to reach the scientists, and another five years for a solution to be received.

"Ten years is really too long to wait, so the craft needs a highly capable artificial intelligence, so that it can figure out solutions to problems with a high degree of autonomy," they note.

If a technological Singularity happens, all bets are off. However, again as a worse case, I assume here that a Singularity does not happen, or fully simulating an astronaut does not happen. So human monitoring and control will still be needed.

The mind-uploading solution

The very high cost of a crewed space mission comes from the need to ensure the survival and safety of the humans on-board and the need to travel at extremely high speeds to ensure it's done within a human lifetime.

One way to overcome that is to do without the wetware bodies of the crew, and send only their minds to the stars - their "software" — uploaded to advanced circuitry, augmented by AI subsystems in the starship's processing system.

The basic idea of uploading is to "take a particular brain [of an astronaut, in this case], scan its structure in detail, and construct a software model of it that is so faithful to the original that, when run on appropriate hardware, it will behave in essentially the same way as the original brain," as Oxford University's Whole Brain Emulation Roadmap explains.

It's also known as "whole brain emulation" and "substrate-independent minds" — the astronaut's memories, thoughts, feelings, personality, and "self" would be copied to an alternative processing substrate — such as a digital, analog, or quantum computer.

An e-crew — a crew of human uploads implemented in solid-state electronic circuitry — will not require air, water, food, medical care, or radiation shielding, and may be able to withstand extreme acceleration. So the size and weight of the starship will be dramatically reduced.

Combined advances in neuroscience and computer science suggest that mind uploading technology could be developed in this century, as noted in a recent Special Issue on Mind Uploading of the International Journal of Machine Consciousness.

Creating a brain

MIT neuroscientist Sebastian Seung has speculated that if models of brains become increasingly accurate, eventually there must be a simulation indistinguishable from the original.

In fact, "neuroscience is ready for a large-scale functional mapping of the entire neural circuits," Harvard scientist George Church and other researchers conclude in a landmark 2012 Neuronpaper.

I suggest that developing mind-uploading technology for software e-crews may make the 100YSS project practical, while delivering equally important spinoffs in neuroscience, computer science, and longevity, perhaps even including indefinite life extension.

The new brain can be much more resistant and long-lived than the old biological brain, and it can be housed in a similarly resistant and long-lived robotic body. Robots powered by human uploads can be rugged, resistant to the vacuum and the harsh space environment, easily rechargeable, and much smaller and lighter than wetware human bodies.

Eventually, human uploads augmented by AI subsystems can be implemented in the solid-state circuitry of the starship's processing system.

Boredom and isolation will not be a problem for e-crew members, because the data processing system of a miniaturized starship will be able to accommodate hundreds and even thousands of human uploads.

Light sails

The huge reduction in weight resulting from uploading would allow for radical propulsion systems, such as "light sails" (aka "solar sails") - spacecraft driven by light energy alone. The Planetary Society currently has a research project to develop light sails .

The low mass of light sails — combined with the e-crew's ability to withstand extreme acceleration — might allow for achieving a substantial fraction of the speed of light, so the time to go to the stars would be significantly reduced.

E-crewed interstellar missions have been described by science fiction writers. Greg Egan was one of first in Diaspora. In Charlie Stross‘s Accelerando, the coke-can-sized starship Field Circus, propelled by a Jupiter-based laser and a light sail, visits a nearby star system with an e-crew of 63 uploaded persons who have a hell of a lot of fun on the way. Stross writes:

Here we are, sixty something human minds. We've been migrated — while still awake — right out of our own heads using an amazing combination of nanotechnology and electron spin resonance mapping, and we're now running as software in an operating system designed to virtualize multiple physics models and provide a simulation of reality that doesn't let us go mad from sensory deprivation!

And this whole package is about the size of a fingertip, crammed into a starship the size of your grandmother's old Walkman, in orbit around a brown dwarf just over three light-years from home.

Of course. a light sail powered by lasers back home, can only push a starship on an one-way trip, but the data from the uploaded astronauts would will be beamed home via the Interplanetary Internet.

The "starwisp" concept proposed by Robert L. Forward is a variation of a light sail remotely driven by a microwave beam instead of visible light (but has known problems).

Sideloading

One problem with implementing mind uploading is that it's plagued by metaphysical discussions about the continuity of personal identity ("is only a copy"), which are irrelevant here. Even if I thought that uploads will only be copies, I would be not only happy, but also grateful and honored if my upload copy could participate in the first interstellar mission.

But even coarse, preliminary uploading technology could be sufficient. "Sideloading," proposed by science fiction writer Greg Egan in Zendegi, is the process of training a neural network to mimic a particular organic brain, using a rich set of non-invasive scans of the brain in action.

Egan describes a "Human Connectome Project," completed in the late 2020s, that produces detailed connectome maps from brain scans of thousands of volunteers. The maps could be used to build an average human neural network, which could serve as a model of a generic human brain.

Then the model could be tweaked and fine-tuned to emulate a specific living person, using in-vivo brain scans and supervised training sessions in a VR environment. In Zendegi, the resulting personalized model passes the Turing Test and often behaves as a convincing emulation of the original.

Why not send AI's?

If strong AI is developed, perhaps smarter than humans, why should we bother to upload humans? One answer is that most of us will want human minds on our first journey to the stars.

However, I agree with Ray Kurzweil's speculation that we will merge with technology, so many future persons will not be "pure" humans or pure AIs, but rather hybrids, blended so tightly that it will be impossible to tell which is which.

Ultimately, I think space will not be colonized by squishy, frail and short-lived flesh-and-blood humans. As Sir Arthur C. Clarke wrote in Childhood's End, perhaps "the stars are not for Man" — that is, not for biological humans 1.0.

It will be up to our postbiological mind children, implemented as pure software based on human uploads and AI subsystems, to explore other stars and colonize the universe. Eventually, they will travel between the stars as radiation and light beams.